1. Field of the Invention
The present invention relates to container trailer assemblies. Additionally, the present invention relates to systems and apparatus for the transport of proppant material. More particularly, the present invention relates to a trailer assembly that is particularly suitable for the transport of containers of proppant material.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Hydraulic fracturing is the propagation of fractions in a rock layer caused by the presence of pressurized fluid. Hydraulic fractures may form naturally, in the case of veins or dikes, or may be man-made in order to release petroleum, natural gas, coal seam gas, or other substances for extraction. Fracturing is done from a wellbore drilled into reservoir rock formations. The energy from the injection of a highly-pressurized fracking fluid creates new channels in the rock which can increase the extraction rates and ultimate recovery of fossil fuels. The fracture width is typically maintained after the injection by introducing a proppant into the injected fluid. Proppant is a material, such as grains of sand, ceramic, or other particulates, that prevent the fractures from closing when the injection is stopped.
With the rise of hydraulic fracturing over the past decade, there is a steep climb in proppant demand. Global supplies are currently tight. The number of proppant suppliers worldwide has increased since 2000 from a handful to well over fifty sand, ceramic proppant and resin-coat producers.
By the far the dominant proppant is silica sand, made up of ancient weathered quartz, the most common mineral in the Earth's continental crust. Unlike common sand, which often feels gritty when rubbed between the fingers, sand used as a proppant tends to roll to the touch as a result of its round, spherical shape and tightly-graded particle distribution. Sand quality is a function of both deposit and processing. Grain size is critical, as any given proppant must reliably fall within certain mesh ranges, subject to downhole conditions and completion design. Generally, coarser proppant allows the higher flow capacity due to the larger pore spaces between grains. However, it may break down or crush more readily under stress due to the relatively fewer grain-to-grain contact points to bear the stress often incurred in deep oil- and gas-bearing formations.
Typically, in any hydraulic fracturing operation, a large amount of such proppant is required. The transport of proppant presents significant issues and difficulties. Fundamentally, governmental roads requirements establish a limit as to the amount of weight that can be transported over the roads. These weight limits are established so as to avoid damage to the structural integrity of the road and also damage to any bridges, overpasses, or other structures associated with the road. Additionally, there are height requirements on such transport vehicles. Conventionally, all transport vehicles should have a height of less than 13½ feet. As such, the transport vehicle can travel on virtually all roads without issues associated with low overlying bridges and overpasses. Additionally, in the transport of proppant, there are a variety of issues related to the safety of the transport. For example, structures should be provided so as to avoid any shifting of the proppant contents in the container that is being transported. Further, concern should also be directed to the center of gravity associated with the contained proppant on the vehicle. If the center of gravity is too high, then there is an increased likelihood of a potential overturning of the vehicle and a reduction in the handling capability of the vehicle.
Conventionally, a 20 foot ISO container could be utilized so as to transport proppant on a conventional container trailer. Unfortunately, experiments have determined that the transport of sand in such conventional containers is not suitable. If the 20 foot ISO is filled with proppant material, then it would certainly exceed the government weight limits on the road. If the 20 foot ISO container were filled with a lesser amount of proppant material, the material could more easily shift in the container and create a dangerous driving condition. Additionally, if a 20 foot ISO container is minimally filled with proppant, the angle of repose of the proppant in the container would make it extremely difficult to completely empty the proppant material from the container. As such, it would not be possible to empty a conventional 20 foot container. As such, a need has developed so as to avoid the use of a 20 foot container for the transport of proppant material.
Importantly, the weight limits that are imposed by government authorities on the transport of goods on road requires that the weight limit be under 80,000 pounds. This weight limit will include the truck, the trailer and the load that is being transported by the truck and trailer. As such, the weight of the vehicle is of a significant concern when determining the amount of proppant that can be moved by a trailer over the roads. As such, it is desirable to minimize the weight of the truck and trailer while still preserving the structural integrity of the truck and trailer.
In the earlier patent applications by the present inventor (for example, U.S. patent application Ser. No. 13/628,702) a 10 foot ISO container was proposed. In this earlier application, it is found that the 10 foot ISO container has a height of 8.5 feet. As such, such a container would contain less than an optimal amount of proppant. In order to deliver the desired 46,500 pounds of proppant to the site, and in order to provide a proper angle of repose of the proppant material within the container, it was found that an ISO container with a height of 9.5 feet was necessary. If such a container of an increased height were actually used on a conventional container trailer, it would exceed the height requirements for the vehicle. If the conventional container trailer were used, the total weight of the vehicle would be in excess of the 80,000 pound limit. Additionally, the placement of the container on the top of a conventional container trailer would increase the center of gravity to the trailer and, as such, increase the potential for vehicle overturns and reduce the handling capability of the truck. Additionally, a standard container trailer could cause the operator to place the sand container in an improper location along the length of the trailer such that the weight is not properly centered for proper transport.
In the past, various patents have issued relating to container trailers. For example, U.S. Pat. No. 3,958,707, issued on May 25, 1976 to D. L. Deppe, discloses a container transport trailer having a bottomless U-shaped support frame including a cross member and a pair of side members. A lift member is connected to the forward end of the trailer and cooperates with a pair of support arms pivotally connected to the rear ends of the side members of the U-shaped flame to engage against the rear portion of the article.
U.S. Pat. No. 5,839,864, issued on Nov. 24, 1998 to S. K. Reynard, teaches a locking system for a container-carrying trailer having a loading platform on which a container can be mounted. The locking system comprises a forward pair of locking devices and a rearward pair of locking devices mounted at forward and rear ends of the loading platform. The locking device is cooperative with respective corner fittings of the container in order to clamp the container to the loading platform.
U.S. Pat. No. 6,109,684, issued on Aug. 29, 2000 to M. A. Reitnouer, discloses a flatbed trailer design that unitizes the three main components of a trailer bed, i.e. the main rails, the cross members and the floor, to create a lightweight and stronger trailer. The trailer design comprises two main rails having dual webs and a plurality of shouldered cross members. These dual web main rails and shouldered cross members have top flanges that are formed by the upper plane of the flooring members. In addition, intermediate flooring supports are used between cross members.
U.S. Pat. No. 7,866,933, issued on Jan. 11, 2011 to Welch et al., teaches a container trailer that includes a coupling to attach the trailer to a tractor, and a frame attached to the coupling. The frame is positioned as a single unit about a container such that the frame can be attached to the container in four regions of the container to lift the container. The trailer has road wheels for long-haul transportation. The trailer frame can be positioned about the container by laterally expanding and retracting, pivoting about a horizontal axis, and pivoting about a vertical axis.
U.S. Pat. No. 8,182,193, issued on May 22, 2012 to Gaudet et al., shows a trailer for transporting freight a container. The trailer has a frame with a front frame section which is adapted to be coupled to a suitable road vehicle. A pair of displaceable horizontal side beams are secured to the front frame section and are provided with a hingeable rear gate formed by a pair of hinge arms. Each of the side beams has a suspension assembly to support a tandem wheel arrangement. Retractable vertical lifting piston cylinders are secured to a portion of the front frame and to the pair of hinge arms and are actuable to lift the pair of horizontal side beams and its wheels above a ground surface. Laterally extendable piston cylinders are also secured to the front frame and the hinge arms to displace the horizontal side beams outwardly and inwardly with respect to one another when lifted off the ground surface. Container lifting posts are secured to opposed ends of the front frame section and the hinge arms for removable connection to a container positioned between the side beams to lift and lower the container therebetween. Container connectors are secured to each of the side beams for securing a container thereto for transportation.
U.S. Patent Publication No. 2013/0004272, published on Jan. 3, 2013 to M. Mintz, provides an apparatus for transporting proppant for use in standard ISO intermodal container and for delivering the proppant to well sites. The apparatus is configured for being inserted into a standard 20 foot container and adapted for transporting frac sand and proppant from a quarry to a well site. A plurality of inlet ports are disposed atop the roof, with the inlet ports receiving the proppant from a proppant supply source into a funnel/hopper. A plurality of outlet ports received the proppant within the funnel/hopper and deliver the proppant to the well site. An in situ valve is disposed within the hopper assembly for effectuating industry standard continuous pressurized discharge of stored proppant material into a discharge pipe for delivery downhole.
It is an object of the present invention to provide a trailer assembly that is able to effectively transport a 10 foot ISO container.
It is another object of the present invention to provide a trailer assembly that facilitates the transport of proppant in containers positioned thereon.
It is another object of the present invention to provide a trailer assembly which is of minimal of weight so as to facilitate the delivery of a maximum amount of proppant within the container positioned thereon.
It is still another object of the present invention to provide a trailer assembly which minimizes the center of gravity of the proppant-containing container positioned thereon.
It is still another object of the present invention to provide a trailer assembly which allows multiple empty proppant containers to be positioned thereon.
It is still a further object of the present invention to provide a trailer assembly which allows the proppant-containing container to meet height and weight requirements during the transport of proppant.
It is still another object of the present invention to provide a trailer assembly which is easy to use, relatively inexpensive and easy to manufacture.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.